Parabolic combustion engine

ABSTRACT

A cylinder for an internal combustion engine comprising at least one combustion chamber and a squish area disposed at or around a base of the at least one combustion chamber, wherein the at least one combustion chamber comprises a paraboloidal cavity.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/484,076 filed on Apr. 10, 2017, now U.S. Pat. No. 10,352,267.

FIELD OF THE INVENTION

The present invention relates generally to an internal combustion enginehaving a parabolic-shaped combustion chamber within a cylinder head. Theapparatus and method may be utilized with all different engines,including but not limited to two-cycle engines, four-cycle engines, ordiesel engines.

BACKGROUND OF THE INVENTION

In internal combustion engines, various shapes have been utilized withinthe cylinder head of a combustion chamber. Some of the common shapesthat have been used include the L-head/flathead configuration; the“bathtub” configuration; the hemispherical (“hemi”) configuration; the“wedge” configuration; and the “pent-roof” configuration. Many of theseconfigurations provide certain advantages within certain types ofengines. For example, the L-head/flathead configuration has proven to beparticularly useful in side-valve engines. Additionally, the bathtub,hemi, and wedge configurations have been proven to be particularlyuseful in overhead valve engines. However, even in many of theconfigurations that have been attempted, there is still room to furtherincrease horsepower, reduce emissions, and increase efficiency.

In addition to the foregoing, a squish area has been utilized in thecylinders of certain internal combustion engines to provide enhancedcompression during the engine cycle. A squish area is generally createdbetween a piston top surface and the lower surface of a cylinder headforming the combustion chamber. A squish area provides severaladvantages, including enhanced combustion, and the resultant squish flowfunctions not only to stir the intake air but also to transfer theintake air toward a sparkplug disposed close to the center of thecombustion chamber. Despite the foregoing advantages, many engines donot utilize a squish area in a cylinder and therefore do not realize theattendant advantages of improved efficiency or enhanced compression.

Therefore, a need in the art exists for a new internal combustion enginewith enhanced power output, increased efficiency, and smoother running.

SUMMARY OF THE INVENTION

It is therefore a primary object, feature, and/or advantage of thepresent invention to provide an improved internal combustion engine thatovercomes deficiencies in the prior art.

It is another object, feature, and/or advantage of the present inventionto provide an internal combustion engine having a parabolic-shapedcombustion chamber.

It is another object, feature, and/or advantage of the present inventionto provide an internal combustion engine having a squish area within atleast one cylinder.

It is another object, feature, and/or advantage of the present inventionto provide an internal combustion engine having a squish ratio ofgreater than 0.5.

It is another object, feature, and/or advantage of the present inventionto provide an internal combustion engine having a cylinder with asparkplug that is offset from the top center of the combustion chamber.

It is another object, feature, and/or advantage of the present inventionto provide an internal combustion engine having a cylinder with aparabolic combustion chamber having a fuel injection port to allow fordirect fuel injection to the parabolic combustion chamber.

These and/or other objects, features, and advantages of the presentinvention will be apparent to those skilled in the art. The presentinvention is not to be limited to or by these objects, features andadvantages, and no single embodiment need exhibit every object, feature,and/or advantage.

According to one aspect of the present invention, a cylinder for aninternal combustion engine having a combustion chamber comprising aparaboloidal cavity is provided. The cylinder includes a piston, acylinder head, and a cylinder body where a perimeter of the piston headand a bottom portion of the cylinder head comprise a squish area. Theparaboloidal cavity is preferably defined by an elliptic paraboloid(also referred to as a paraboloid of revolution). The cylinder head andcylinder body may be fabricated as separate pieces or as a unitarystructure.

According to another aspect of the present invention, the cylinder mayalso include a port for a sparkplug positioned at a top portion of thecylinder head, so that when a sparkplug is situated within the port, anelectrode of the sparkplug rests within the paraboloidal cavity. Incertain embodiments, the electrode of the sparkplug may be positioned ator near a focal point of the paraboloidal cavity. In one illustratedembodiment, the sparkplug port is positioned at the top center of thecylinder head. In another illustrated embodiment, the sparkplug port isoffset from the top center of the cylinder head.

According to another aspect of the present invention, a method formaking a cylinder for an internal combustion engine is provided. Themethod includes forming a cylinder head comprising a paraboloidal cavityand a base portion, associating a cylinder body with the cylinder head,and placing a piston within the cylinder body so that an outer perimeterof a crown of the piston and the base portion of the cylinder head forma squish area.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a cylinder of an internal combustionengine having a combustion chamber and piston configuration inaccordance with a first embodiment of the present invention where acombustion chamber comprising a paraboloidal cavity is utilized inconjunction with a squish area at the base of the combustion chamber.

FIG. 2 is a cross-sectional view of a cylinder of an internal combustionengine having a combustion chamber and piston configuration inaccordance with a second embodiment of the present invention where asparkplug is offset from the centerline of the cylinder.

FIG. 3 is a cross-sectional view of a cylinder of an internal combustionengine having a combustion chamber and piston configuration inaccordance with a third embodiment of the present invention where asparkplug is offset from the centerline of the cylinder and a directfuel injection port and nozzle are incorporated into the top of thecylinder.

FIG. 4 is a cross-sectional view of a cylinder of an internal combustionengine having a combustion chamber and piston configuration inaccordance with a fourth embodiment of the present invention having avolumetrically-enhanced piston top.

DETAILED DESCRIPTION OF EMBODIMENTS

The present invention relates generally to a parabolic-shaped combustionchamber cylinder head that is used to increase the horsepower ofprimarily, but not limited to, any two-cycle engine. It may also beadapted to function in any four-cycle engine or diesel engine. Aparabolic surface focuses light rays in essentially straight lines asevidenced by a searchlight or spotlight. This invention applies the sameprinciple to focus straight lines of force caused by the combustion ofengine gases within a combustion chamber in an internal combustionengine and direct them in straight lines toward the crown of a piston.This causes the piston in the engine to move downward with increasedforce, resulting in increased horsepower for the engine.

The cylinder head comprising a parabolic-shaped combustion chamberpreferably employs a squish area. “Squish” is an effect in internalcombustion engines which creates turbulence of the fuel/air mixture asthe piston approaches the combustion chamber. In an engine utilizing asquish area, an outer perimeter of the piston crown comes very close tothe cylinder head during operation. As such, the “squish area” is thearea within a cylinder of an internal combustion engine that is made tovery nearly come into contact with the piston when the piston is at topdead center. As a piston approaches a squish area, the gases present arecompressed and then suddenly pushed out of the squish area and withinthe combustion chamber, creating turbulence. This promotes thoroughfuel/air mixing, a factor beneficial to efficient combustion. Squishareas are generally utilized in a few types of internal combustionengines, including overhead valve engines and overhead camshaft engines.The present invention utilizes both a parabolic combustion chamber in acylinder head and a squish area at a base of the cylinder head toprovide enhanced horsepower and efficiency.

Referring now to the drawing wherein like numerals refer to like parts,FIG. 1 is a cross-sectional view of a cylinder of an internal combustionengine in accordance with a first embodiment, depicted as cylinder 40comprising a cylinder head 42 and cylinder body 44. The cylinder head 42includes a parabolic combustion chamber 2, a port 46 for accepting asparkplug 4, and a base portion 48. The cylinder body 44 includes anintake port 20, an exhaust port 22, and a piston 36 disposed within thecylinder body 44. The cylinder body 44 further includes a cylinder borewith a cylinder bore diameter 24.

In this first embodiment, a squish area 12 may be seen at the base ofthe parabolic combustion chamber 2. The squish area 12 is shown as beingangled with respect to the top of piston 36, denoted by squish angle 16.In the illustrated configuration, any gases within the squish area 12during operation of the piston 36 will be expelled toward the center ortop of the parabolic combustion chamber 2. Therefore, an angledconfiguration of the squish area is preferred but not required. Asappreciated by those of skill in the art, other configurations of thesquish area 12 are within the scope of this invention. For instance, aconfiguration where the squish area is coplanar with a flat piston headwill still provide the attendant advantages of a squish area, eventhough such an embodiment is not angled.

The parabolic combustion chamber 2 comprises a paraboloidal cavity.Preferably, the paraboloidal cavity may be defined by athree-dimensional surface produced by the following equation.

$z = {\frac{x^{2}}{a^{2}} + \frac{y^{2}}{b^{2}}}$

This equation represents an elliptic paraboloid as a three-dimensionalsurface, in a suitable coordinate system with three axes (x, y, and z),where a and b are constants that dictate the level of curvature in thexz and yz planes respectively. Alternatively, the paraboloidal cavitymay be approximated by utilizing various techniques, including throughthe use of commercial CAD drawing software suites. For instance, someCAD software programs include a parabola utility, where a paraboliccurve may be placed in a three-dimensional workspace and revolved aroundan axis to create a paraboloid. Alternatively or additionally, theparaboloidal cavity may be approximated utilizing various knowntechniques, such as those taught in Frank Schubert's article entitled,“Quick Way to Approximate Parabolas,” published in Machine Design 56,no. 1 at 140-140 (1984), which is incorporated by reference in itsentirety.

The volume of the parabolic combustion chamber 2 may be calculated byusing the formula for volume of a paraboloid, where r is the radius ofthe rim at the base or top of the paraboloid, and h is the height of theparaboloid.

V=½π(r ² h)

In addition, a nose of the sparkplug 4 may be positioned such that aspark produced by the sparkplug 4 will be presented at or near the focalpoint 6 of the parabolic combustion chamber 2. This concept has somelimitations for very small cylinder heads due to the size of availablesparkplugs. An extended nose sparkplug may be utilized as well, as thiswill place the spark further into the parabolic combustion chamber. Assuch, if one wishes to utilize a parabolic combustion chamber where thespark will be at the focal point of the parabolic combustion chamber,the formula for the paraboloidal cavity should be modified toaccommodate this change in focal point. Other types of ignition devicesmay also be considered, but it is highly desirable for such devices toplace a spark at or near the focal point 6 of the paraboloidalcombustion chamber 2. In the embodiment shown in FIG. 1, the electrodeof sparkplug 4 is placed near the focal point 6 of parabolic combustionchamber 2 so that a spark may be generated at the focal point 6.

It should be understood that these general principles regarding thenature of the parabolic combustion chamber may apply to each of theparaboloidal cavities present in other embodiments of this invention.

The embodiment shown in FIG. 1 includes a unitary cylinder. In otherwords, the cylinder head 42 and cylinder body 44 are depicted as asingle structure. As such, in order to manufacture the cylinder head 42and cylinder body 44 as depicted in FIG. 1, they must be fabricated orotherwise produced as one unit. However, it may be advantageous for manyreasons to fabricate or produce cylinder head 42 and cylinder body 44 asseparate pieces. This may provide cost advantages in manufacturing, asthe various components may be machined in different ways. In embodimentswhere cylinder head 42 and cylinder body 44 are produced as separatepieces, those pieces may be attached in many different ways, includingbut not limited to welding, threading, bolts, or tie rods so as toresult in cylinder 40.

In operation, the embodiment of a cylinder for an internal combustionengine shown in FIG. 1 is generally the same as most two-cycle engines.First, a fuel/air mixture is drawn into the parabolic combustion chamber2 through intake port 20 by movement of the piston 36. As the piston 36rises, it compresses the fuel/air mixture, urging the fuel/air mixtureinto parabolic combustion chamber 2. In addition to creatingcompression, the upward movement of the piston 36 creates squish flow asthe fuel/air mixture interacts with squish area 12 to compress thefuel/air mixture introduced by intake port 20 and urge the fuel/airmixture toward sparkplug 4 disposed at or near the focal point 6 of theparabolic combustion chamber 2. At some timing distance from the top ofthe stroke, the sparkplug 4 ignites the compressed fuel/air mixture. Theburning fuel expands, driving the piston 36 downward. As the piston 36is urged downward, this exposes the exhaust port 22, allowing anyexhaust to exit the cylinder 40. While the depicted embodimentsprimarily relate to two-cycle engines, it should be appreciated thatthis invention is not so limited. This invention may be adapted for anyengine, including but not limited to four-cycle engines or dieselengines.

In a second embodiment illustrated in FIG. 2, a sparkplug 204 and port246 for accepting the sparkplug are offset from the centerline C of thecylinder 240. As with the first embodiment, the cylinder 240 includes acylinder head 242 and cylinder body 244. The cylinder head 242 includesa parabolic combustion chamber 202, and a port 246 for acceptingsparkplug 204. A squish area 212 may be seen at the base 248 of theparabolic combustion chamber 202. Disposed within the cylinder body 244is a piston 236, and the cylinder body includes an intake port 220 andexhaust port 222. The primary difference between the embodiments ofFIGS. 1 and 2 lies in the disposition of the sparkplug 204 and port 246with respect to the cylinder 240. In the embodiment shown in FIG. 2, theelectrode of sparkplug 204 is placed at or near the focal point 206 ofparabolic combustion chamber 202 despite the sparkplug 204 being offsetfrom the centerline of the cylinder 240. While not required, it isadvantageous to maintain the electrode of the sparkplug at or near thefocal point of the parabolic combustion chamber to maximize theattendant advantages of utilizing a parabolic combustion chamber.

FIG. 2 provides an embodiment where it may be advantageous to orient asparkplug to satisfy a particular design constraint. As a non-limitingexample of such a design constraint: in certain small engines, such asthose used in lawnmowers, line or string trimmers, chainsaws or thelike, the equipment design may dictate that the engine be positioned ina manner that hinders technician access to the sparkplug. In such cases,a configuration such as that shown in FIG. 1 may be acceptable, but thetechnician may have to remove housings or otherwise disassemble theequipment to access the sparkplug. By offsetting the sparkplug 204 fromthe centerline C of the cylinder 240 by some angle A as shown in FIG. 2,this may provide the advantage of allowing a technician or user of theengine to access the sparkplug without having to remove housings ordisassemble the equipment.

In addition to addressing certain design constraints, there are otheradvantages of offsetting the sparkplug from the centerline of thecylinder, such as providing for direct fuel injection into thecombustion chamber as shown in the embodiment illustrated in FIG. 3.FIG. 3 is similar in certain respects to the embodiment illustrated inFIG. 2; however, the embodiment of FIG. 3 has been modified to allow fordirect fuel injection into the parabolic combustion chamber. As with theembodiment shown in FIG. 2, the cylinder 340 includes a cylinder head342 and cylinder body 344. The cylinder head 342 includes a paraboliccombustion chamber 302 and a port 346 for accepting sparkplug 304. Thecylinder head 342 further includes a fuel injection port 350 and a fuelinjection nozzle 332 disposed therein. A squish area 312 may be seen atthe base 348 of the parabolic combustion chamber 302. Disposed withinthe cylinder body 344 is a piston 336. The advantages of utilizingdirect fuel injection are decreased emissions and increased engineefficiency. For example, in two-cycle engines, the intake port is nolonger required.

In the embodiment illustrated FIG. 3, the electrode of sparkplug 304 isplaced at the focal point 306 of parabolic combustion chamber 302despite the sparkplug 304 being offset from the centerline of thecylinder 340 and the presence of the fuel injection nozzle 332. Whilenot required, it is advantageous to maintain the electrode of thesparkplug at or near the focal point of the parabolic combustion chamberto maximize the attendant advantages of utilizing a parabolic combustionchamber.

In operation, the embodiment of a cylinder for an internal combustionengine shown in FIG. 3 differs from that of most two-cycle engines.First, fuel is injected into the parabolic combustion chamber 302through fuel injection port 350 when piston 336 is descending. As thepiston 336 completes its downward cycle and begins to rise, it begins tocompress the fuel within the cylinder 340, urging the fuel intoparabolic combustion chamber 302. In addition to creating compression,the upward movement of the piston 336 creates squish flow as the fuelinteracts with squish area 312 and urges the fuel toward sparkplug 304disposed at or near the focal point 306 of the parabolic combustionchamber 302. At some point in the stroke, the sparkplug 304 ignites thecompressed fuel. The burning fuel expands, again driving the piston 336downward.

FIG. 4 shows a fourth embodiment of the invention, where a pistonconfiguration is utilized to further enhance compression. This fourthembodiment utilized a curved, domed, or otherwise volumetricallyenhanced piston top. As shown in FIG. 4, a domed portion 428 may beincorporated onto the top or crown of piston 436. This addition to thepiston surface reduces the volume of the parabolic combustion chamber402 when the piston is at the top of a stroke, thus raising thecompression ratio of the engine. Domed portion 428 shows the volume ofthe added curved piston top. Various other shapes such as a truncatedfrustum of a cone may also be employed instead of a dome. The radius ofthe domed portion 428 may be established by setting a line perpendicularto the squish angle 416 and drawing it downward to intersect thecenterline of the piston 436 diameter. The embodiment of FIG. 4 includesa squish area 412 and focal point 406.

A method for making a cylinder for an internal combustion engine isprovided below. The method includes forming a cylinder head comprising aparaboloidal cavity and a base portion, associating a cylinder body withthe cylinder head, and placing a piston within the cylinder body so thatan outer perimeter of a crown of the piston and the base portion of thecylinder head form a squish area. Alternatively, the cylinder body andcylinder head may be formed as one piece, as described above. Ports maybe formed in the cylinder head, including but not limited to a sparkplugport and/or a fuel injection port. The sparkplug port may be formed inthe cylinder head to align with a centerline of the cylinder body, oroffset from the centerline. The cylinder body may include an intake portand an exhaust port. Most of these components may be formed by any knownmanufacturing process for engine parts, such as machining, molding,injection molding, CNC machining, or the like.

The illustrated embodiments as described include where the internalcombustion engine is a single cylinder, two-cycle engine. However, theprinciples of this invention may apply to any type of engine, such as afour-cycle engine, a multi-cylinder engine, and/or a diesel engine.However, it has been found that this invention is particularly suitedfor two-cycle engines, particularly single cylinder, two-cycle engines.

In all embodiments, it may be advantageous to utilize a squish ratiogreater than 0.5 . Generally, when a squish ratio is greater than 0.5 ina cylinder, an engine containing such a cylinder is considered to be ahigh performance engine. This ratio is calculated by dividing the squishdiameter by the cylinder bore diameter. If the resultant ratio isgreater than 0.5 for the cylinder, then an engine that includes thecylinder may be considered a high performance engine. As a non-limitingexample, the cylinder of FIG. 1 includes squish diameter 18 and cylinderbore diameter 24. Dividing the squish diameter 18 by the cylinder borediameter 24 will provide the squish ratio for cylinder 40.

The disclosed embodiments have many attendant advantages. As a firstexample, cylinders having a parabolic combustion chamber will produceenhanced horsepower in the engines that contain them. As a secondexample, cylinders having a squish area will exhibit enhanced efficiencyand horsepower. Those engines with a cylinder having both a paraboliccombustion chamber and a squish area will heighten these advantages. Asa third example, a volumetrically enhanced piston top or crown willprovide the advantage of enhancing compression within the cylinder. Inaddition, utilizing direct fuel injection in a cylinder having aparabolic combustion chamber will result in an engine with decreasedemissions and increased efficiency.

It should be understood that various changes and modifications to theembodiments described herein will be apparent to those skilled in theart. Such changes and modifications may be made without departing fromthe spirit and scope of the present invention and without diminishingits attendant advantages. It is, therefore, intended that such changesand modifications be covered by any claims.

1. An apparatus comprising: a cylinder having at least one combustionchamber and a squish area having a non-zero squish angle disposed at oraround a base of the at least one combustion chamber; wherein the atleast one combustion chamber comprises a paraboloidal cavity; whereinthe cylinder has a squish ratio greater than or equal to 0.5; andwherein the cylinder is adapted to position an electrode of a sparkplugat or near a focal point of the paraboloidal cavity.
 2. The apparatus ofclaim 1, wherein the cylinder includes a cylinder body and a cylinderhead.
 3. The apparatus of claim 2, wherein the cylinder body andcylinder head are of a unitary construction.
 4. The apparatus of claim2, wherein the cylinder head comprises the at least one combustionchamber and a sparkplug port.
 5. The apparatus of claim 4, wherein thecylinder head further comprises a fuel injection port.
 6. The apparatusof claim 5, wherein the fuel injection port is offset from a centerlineof the cylinder.
 7. The apparatus of claim 6, wherein the sparkplug portis offset from the centerline of the cylinder.
 8. The apparatus of claim1, wherein the cylinder further comprises at least one piston, whereinthe at least one piston comprises a piston top.
 9. The apparatus ofclaim 8, wherein an axis of symmetry of the paraboloidal cavitycoincides with a centerline of the cylinder or a center of the pistontop.
 10. The apparatus of claim 8, wherein the piston top comprises avolumetrically-enhanced portion that extends into the paraboloidalcavity when the piston is at top dead center.
 11. A method of making acylinder for an internal combustion engine, comprising: forming acylinder comprising at least one combustion chamber having aparaboloidal cavity and a squish area having a non-zero squish angledisposed at or around a base of the at least one combustion chamber;adapting the cylinder to include a sparkplug port, whereby an electrodeof a sparkplug may be positioned at or near a focal point of theparaboloidal cavity via the sparkplug port; wherein the cylinder has asquish ratio greater than or equal to 0.5.
 12. The method of claim 11,wherein forming the cylinder comprises machining, molding, injectionmolding, or CNC machining.
 13. The method of claim 12, wherein adaptingthe cylinder comprises machining, cutting, molding, injection molding,or CNC machining.
 14. The method of claim 13, wherein the cylindercomprises a cylinder body and a cylinder head.
 15. The method of claim14, wherein the cylinder body and cylinder head are formed of a unitaryconstruction.
 16. The method of claim 14, wherein the cylinder headcomprises the at least one combustion chamber and the sparkplug port.17. The method of claim 16, further comprising forming a fuel injectionport in the cylinder head.
 18. The method of claim 17, wherein formingthe fuel injection port within the cylinder head comprises machining,cutting, molding, injection molding, or CNC machining.
 19. The method ofclaim 18, wherein the fuel injection port is formed offset from acenterline of the cylinder.
 20. The method of claim 18, wherein thesparkplug port is formed offset from the centerline of the cylinder.